0153

0153-THERMOSTAT CONTROL CIRCUIT HIGH





For a complete wiring diagram Consult Diagrams/Electrical

- When Monitored:
With the engine running.

- Set Condition:
The PCM detects that the Thermostat control circuit voltage is above the maximum acceptable value.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding.Initial Inspection and Diagnostic Overview

Diagnostic Test

1. DTC IS ACTIVE
Turn the ignition on.
With the scan tool, read DTCs.
Record all DTC and applicable Freeze Frame information.
With the scan tool, clear DTCs.
Cycle the ignition off for at least one minute.
Start the engine and allow it to reach operating temperature. If the engine will not start, crank the engine over for at least 10 seconds.

WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose fitting clothing. Failure to follow these instructions can result in personal or fatal injury.

With the scan tool, read DTCs.
Does this DTC reset?

Yes

- Go to 2

No

- Refer to the *CHECKING FOR AN INTERMITTENT DTC Diagnostic Procedure.Checking for an Intermittent DTC

2. THERMOSTAT WIRING AND CONNECTOR INSPECTION
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Thermostat and the Powertrain Control Module (PCM).
Look for any chafed, pierced, pinched, or partially broken wires.
Look for broken, bent, pushed out or corroded terminals.
Search for any Technical Service Bulletins that may apply.
Were any problems found?

Yes

- Repair as necessary.
- Perform the PCM Verification Test.Powertrain Verification Test

No

- Go to 3

3. THERMOSTAT CONTROL CIRCUIT SHORTED TO VOLTAGE




Turn the ignition off.
Disconnect the Thermostat connector.
Disconnect the Powertrain Control Module (PCM) connector.
Turn the ignition on.
Measure the voltage of the Thermostat Control circuit in the Thermostat harness connector.
Is there any voltage present?

Yes

- Repair the Thermostat Control circuit for a short to voltage.
- Perform the PCM Verification Test.Powertrain Verification Test

No

- Go to 4

4. THERMOSTAT CONTROL CIRCUIT SHORTED TO THE FUSED MAIN RELAY OUTPUT CIRCUIT




Turn the ignition off.
Measure the resistance between the Thermostat Control circuit and the Fused Main Relay Output in the Thermostat harness connector.
Is the resistance below 100 ohms?

Yes

- Repair the Thermostat Control circuit for a short to the Fused Main Relay Output circuit.
- Perform the PCM Verification Test.Powertrain Verification Test

No

- Go to 5

5. THERMOSTAT CONTROL CIRCUIT OPEN OR HIGH RESISTANCE




Measure the resistance of the Thermostat Control circuit between the Thermostat harness connector and the Powertrain Control Module (PCM) harness connector.
Is the resistance below 5.0 ohms?

Yes

- Go to 6

No

- Repair the Thermostat Control circuit for an open circuit or high resistance.
- Perform the PCM Verification Test.Powertrain Verification Test

6. THERMOSTAT
Turn the ignition off.
Connect the Powertrain Control Module (PCM) connector.
Replace the Thermostat.
Turn the ignition on.
With the scan tool, clear DTCs.
Cycle the ignition off for at least one minute.
Start the engine and allow it to reach operating temperature.

WARNING: When the engine is operating, do not stand in direct line with the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear loose fitting clothing. Failure to follow these instructions can result in personal or fatal injury.

With the scan tool, read DTCs.
Does this DTC reset?

Yes

- Go to 7

No

- Test Complete.
- Perform the PCM Verification Test.Powertrain Verification Test

7. POWERTRAIN CONTROL MODULE (PCM)
Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Thermostat and the Powertrain Control Module (PCM).
Look for any chafed, pierced, pinched, or partially broken wires.
Look for broken, bent, pushed out or corroded terminals.
Search for any Technical Service Bulletins that may apply.
Were any problems found?

Yes

- Repair as necessary.
- Perform the PCM Verification Test.Powertrain Verification Test

No

- Replace and program the Powertrain Control Module (PCM).
- Perform the PCM Verification Test.Powertrain Verification Test